Marine fuel oil, sometimes referred to as bunker fuel, has traditionally provided a use for heavy oil fractions that are otherwise difficult and/or expensive to convert to a beneficial use. Due in part to use of fuels allowed to have relatively high sulfur content in international waters, vacuum resid fractions as well as other lightly processed (or even unprocessed) fractions can be incorporated into traditional fuel oils.
More recently, many countries have adopted local specifications for lower sulfur emissions from marine vessels. This can result in some vessels carrying two types of fuel oil, with one type being suitable for international waters while a second type can be used while satisfying the more stringent local regulations.
U.S. Pat. No. 5,997,723 describes methods for blending petroleum oils to avoid incompatible blends. Petroleum oils can be characterized based on a solubility number (SBN) and an insolubility number (IN). The goal during blending can be to select blends that either maintain a desired ratio of solubility number to insolubility number, such as at least 1.3, or to select blends having a minimum difference between solubility number and insolubility number, such as at least 20. The solubility number for a blend of petroleum oils is described as a weighted average of the solubility numbers for the individual components.
U.S. Pat. No. 4,441,890 describes use of alkaryl sulfonic acid additives for reducing or inhibiting the formation of asphaltic sediment in fuel oils.
U.S. Pat. No. 8,987,537 describes low sulfur marine fuel compositions, such as a sulfur content of 0.1 wt % or less. The fuel compositions are formed by combining 50 to 90 wt % of a resid fraction, such as an atmospheric resid, with 10 to 50 wt % of an additional hydrocarbon component that is optionally a hydroprocessed hydrocarbon component.
French Publication No. FR 3011004 describes marine fuel compositions formed by blending a heavy distillate boiling range fraction from a cracking process, optionally after hydrotreatment, with a straight run distillate fraction or hydrotreated distillate fraction.